I've been inspecting these two multiplexer and I realized very little difference between them. One of the differences that I spotted that ADG788 requires spesific power sequencing, but in ADG734's datasheet there is no advice on power sequencing.
Does one of them requires power sequencing and the other does not or is it just a lack of information in ADG734's datasheet?
You are correct, there is very little difference between them. The only difference is the available packages. the ADG788 is available in a chip scale package and the ADG734 is available as a TSSOP or QSOP package.